The tri-colour hung at half-mast during the poignant ceremony, where a wreath was laid by Collins' grandniece Helen Collins. The Sliabh na mBan armoured car, which her grand uncle had travelled in the day he was killed at Beal na mBlath, Co Cork, was parked nearby.

Ms Collins, from Cork, said it meant so much to her that soldiers, and not the State, had collected money to pay for the memorial which cost €1,200.

"I actually did not expect myself to feel so emotional about it," she said.

"It makes me feel very strongly connected to Michael Collins and it brings me back to my grandfather and my grandmother and father and all those wonderful memories of family and the loss of all those who have died."

She revealed she "really got to like him and know" Collins when she spoke to a bust of him which sat on her dining room table for four months while the family homestead was being restored some 23 year ago.

Ms Collins - whose grandfather Johnny was Collins' eldest brother - said past generations of her family never held any bitterness despite being burnt out of their home at Woodfield, interned on Spike Island, and Collins' murder.

"But it was always like feeling a loss," she added.

"It was like the table was always set for him and he never came home.

"But I really grew up in a home with no bitterness and total forgiveness."

Unveiling the stonework, Chief of Staff of the Defence Forces, Lieutenant General Conor O'Boyle, said the striking image of the first commander in chief was taken when he returned from a memorial service for seven soldiers killed in the then ongoing Civil War.

"The great tragedy of course was that only a few short days later he was to fall in action himself and become our legendary lost leader, 91 years ago on this day," he said.

A young civilian piper, 14-year-old Alphonsus Culloten, is also in the image dated August 7 1922. He went on to live until his 80s.

Lieutenant General O'Boyle said Collins, in his all too short life, was the essence of service, sacrifice and devotion to the State.

"Throughout this barracks are locations that remind us of General Collins, the direct historical links and his legacy," he continued.

"It was here that he lived as commander in chief of the National Army in 1922 in the modern day School of Music and it was here that he directed operations in the Civil War from the now Brigade Training Centre Building.

"And of course it was from this barracks that he set off to Cork in August 1922 on that fateful visit to his native county."